Tulak Hord. The Majority of his knowledge was hidden away from the rest of the Sith Empire in that Blood relic thing, so ya can't really power-scale him off got any future generation Sith. Also better hype from Khem Val and Traya and Thanaton.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."
I agree, although Tulak's star ship feat, though context-less, beats Ragnos making loud noises with his staff.
But Ragnos seemed more respected and almost worshiped among sith long after his death, which I assume owed more to than just being a great ruler. As you said, though, no way to tell.
Edit: Ragnos also beat a featless sith lord, but that doesn't beat hord (supposedly) soloing countless force users.
__________________ "The power of the dark side is an illness no true Sith would wish to be cured of" -Darth Plagueis
Last edited by Dominis on Dec 23rd, 2014 at 06:02 PM